jsdm/ajax/port.php in J-Web in Juniper Junos before 10.4R13, 11.4 before 11.4R7, 12.1 before 12.1R5, 12.2 before 12.2R3, and 12.3 before 12.3R1 allows remote authenticated users to execute arbitrary commands via the rsargs parameter in an exec action.

Juniper Junos 10.4 before 10.4S15, 11.4 before 11.4R9, 11.4X27 before 11.4X27.44, 12.1 before 12.1R7, 12.1X44 before 12.1X44-D20, 12.1X45 before 12.1X45-D15, 12.2 before 12.2R6, 12.3 before 12.3R3, 13.1 before 13.1R3, and 13.2 before 13.2R1, when Proxy ARP is enabled on an unnumbered interface, allows remote attackers to perform ARP poisoning attacks and possibly obtain sensitive information via a crafted ARP message.

J-Web in Juniper Junos before 10.4R13, 11.4 before 11.4R7, 12.1R before 12.1R6, 12.1X44 before 12.1X44-D15, 12.1x45 before 12.1X45-D10, 12.2 before 12.2R3, 12.3 before 12.3R2, and 13.1 before 13.1R3 allow remote attackers to bypass the cross-site request forgery (CSRF) protection mechanism and hijack the authentication of administrators for requests that (1) create new administrator accounts or (2) have other unspecified impacts.

The kernel in Juniper Junos 10.4 before 10.4R14, 11.4 before 11.4R8, 11.4X27 before 11.4X27.43, 12.1 before 12.1R6, 12.1X44 before 12.1X44-D20, 12.2 before 12.2R4, and 12.3 before 12.3R2, in certain VLAN configurations with unrestricted arp-resp and proxy-arp settings, allows remote attackers to cause a denial of service (device crash) via a crafted ARP request, aka PR 842091.

Memory leak in Juniper JUNOS Packet Forwarding Engine (PFE) allows remote attackers to cause a denial of service (memory exhaustion and device reboot) via certain IPv6 packets.

TCP, when using a large Window Size, makes it easier for remote attackers to guess sequence numbers and cause a denial of service (connection loss) to persistent TCP connections by repeatedly injecting a TCP RST packet, especially in protocols that use long-lived connections, such as BGP.